Thermostatically controlled charger



Jam 7, w47. Q. w. DALZELL THERMOSTATICALLY CONTROLLED CHARGER Filed Nov. 19 1942 frm/1 Patented Jan. 7, 1947 THERMOSTATICALLY CONTROLLED CHARGER Clarence W. Dalzell, West Caldwell, N. J., assignor to Knickerbocker Development Corporation, Belleville, N. J., a corporation of Delaware Application November 19, 1942, Serial No. 466,235

2 Claims.

This invention relates in general to battery chargers for the fast charging of storage batteries and more particularly has reference to the provision of automatic control means in the circuit of the battery charger, and to` indicating means associated with the control means.

In the charging of batteries with the so-called fast chargers current of from 80 to 100 amperes is passed through the battery. In view of the fact that rconsiderable damage could be effected if current at that rate were permitted to flow through the battery under charge without any automatic control battery chargers for this purpose are provided with a plurality of controls operable when an overload is produced in the circuit of the charger including the battery,

or upon short circuiting or overheating of the battery for disconnecting the circuits. Many of these controls are rather complicated and some of them require the battery under charge to have a certain charge in itin order to operate the control device, since they depend for operating current upon current from the battery.

The principal object of the present invention is to provide a battery charger for the fast charging of batteries which is equipped with control and indicating devices of a construction much simpler than those of the prior art.

"Another object of this invention is to provide a fast battery charger provided with control and indicating devices which are not dependent upon the current from the battery for operation thereof.

A further object of this invention is to provide a charger for the fast charging of batteries which includes a transformer having primary and secondary windings, the primary winding of which is connected to a source of current by means of a contactor and the secondary winding of which is included in a circuit together with the battery to be charged and a winding of an actuator for said contactor, said winding being operable upon the iiow of excessive current therethrough to energize the actuator for opening the contactor.

Still another object of this invention is to provide a battery charger for the fast charging of -batteries which includes a transformer having primary and secondary windings, the primary Winding being connected to a source of current by means of a switch thermostatically actuated in response to temperatures of the battery under charge.

A still further object of this invention is to provide a battery charger for the fast charging of batteries which includes a transformer having primary and secondary windings, the primary winding being connected to a source of current by means of a contactor and the secondary winding of which is included in a circuit together with the battery to be charged and a winding of an actuator for said contactor, said winding being operable upon the fiow of excessive current therethrough to energize the actuator for opening the contactor, and in which a switch is incorporated in the connection between the primary of the transformer and the source of current. said switch being thermostatically actuated in response to temperatures of the battery under charge.

It is also an object of this invention to provide a battery charger for the fast charging of batteries in which an overload opened contactor and/or a thermostatically opened switch are provided in the connection between the primary circuit thereof, and in which indicating means responsive to the opening of said contactor and/or switch are provided.

With these and other objects in view which will appear more fully hereinafter, the present invention resides in the circuit, the parts and combinations illustrated in the drawing and hereinafter described.

In the drawing:

Figure 1 is a schematic,view of the circuit of a fast battery charger embodying the features of the present invention,

Figure 2 is a view similar to that of Figure 1 but illustrating a modified form of the present invention.

Referring to the drawing, there is shown in Figure 1 a schematic arrangement of the several circuits of the fast charger embodying the features of the present invention. The transformer I employed in the circuit is provided with a primary windinc.r 2 and a secondary winding 3. The primary winding is tapped, and the several taps are connected to a plurality of switch contacts 4. These contacts cooperate with a switch arm 5 which is connected to one conduit 6 of an alternating current source of power, The other end of the primary windingl of the transformer is connected by a conductor` 'I to one terminal of a contactor 8. Contactor 8 has its other terminal connected by a conductor 9 to one terminal of a thermostatically actuated switch I0. Completion of the circuit through the primary winding 2 of the transformer and through the contactor 8 and switch I0 is eiiected by means of a conductor I I which is connected to the other line I2 of the alternating current power source. A fuse I3 may battery under charge.

3 be incorporated in the conductor II to protect the circuit against extreme overloads.

A fan for cooling the transformer and rectifier is provided and has one terminal of its motor connected by a wire I4 to the conductor 1 and the other terminal of its motor is connected by a wire I5 to a conducting segment I6 of a switch, the movable arm I1 of which is connected to the alternating current conductor 6. The switch arms 5 and I1 are coupled together and are intended to operate in unison so that when the switch arm 5 is engaged with the iirst contact 4, the arm I1 will be brought into conductive engagement with the segment I B. Thus, as soon as the arm 5 is moved into engagement with the rst contact 4, the fan will be placed in operation and will be maintained in operation so long as the switch arm 5 is in engagement with any one of the contacts 4, and so long as the contactor 8 and thermostatic switch II! are closed.

The present invention also provides an indicator which serves to indicate when one or both of the contactor 8 and the switch I8 are open. This indicator, which is in the form of a bell I8, Vis operatively connected with the secondary winding of a bell-ringing transformer I 9, the

primary winding of which is connected by one conductor 28 to the conductor 1 and by another conductor 2I to the conductor II. With this arrangement, even though one of the contactor 8 or switch I 8 is opened, a circuit will be maintained through the primary of the bell-ringing transformer I9, and suiiicient current will flow therethrough to cause the bel1 I8 to ring, and thereby give an audible signal indicating that contactor 8 and/or the switch I0 are open. While the motor of the fan will stop uponopening of the contactor 8 or the switch I 8, sufcient current will flow through said motor and/or the primary 2 of the transformer` I for the effective op eration of the bell I8. f

- Now, since the indicator comprising the bell I8 will operate upon opening of either the contactor 8 or the switch I 8, it is desirable to have some means toY further indicate which of the contactor 8 or switch I'Ois open. For this purpose, the present invention contemplates the provision of a signal light 22 which has its terminals connected to the terminals of the thermostatic switch I0. As long as the switch I 8 is closed,v no current will flow through the light 22, but when the switch I0 is open, the circuit normally completed by the switch I0 will then be completed by the light 22. Since only a small current will now through the lamp 22, this will be insuflicient to cause any diiliculties.

The secondary 3 of the transformer I is connected with a circuit including a rectifier 23, an ammeter 24, the battery 25 to be charged, and a winding 26 of an overload relay. As shown in Figure 1. the rectifier 23 is of the full wave type. and for 'this reason` the secondary 3 of the transformer is tapped intermediate its ends. The battery 25 is connected by means of clips to the conductors 21 and 21' which form part of the circuit including the secondary winding 3 of the transformer. f

Winding 26 of the overload relay serves as a means for energizing an actuating device for opening the contactor 8 included in the circuit with the primary winding of the transformer. The purpose of this construction is to prevent an excessive How of current through the secondary circuit of the transformer which includes the'f' For this reason, the windlof current flowing through winding '26 decreases,

the contactor would close. In accordance with the present invention, however, the movable element of the contactor 8 is mechanically connected to a latch arm 28; one end of which is pivoted and the other end of which is adapted to cooperate with a pivoted pawl 28 which is gravity actuated to latch the bar 28' in a position to'retain the contactor 8 in open position. Obviously, the

pawl28 may be eithergravity actuated or spring pressed. In order to release the movable element of the contactor 8 and enable the same to close, it is necessary to displace the pawl 28 so that the latch bar 28' may be free. This is accomplished by manually actuating the pawl 28, and it is one of the features of the present invention that the means for actuating the pawl 28 or the pawl itself bevvisible so that by a mere inspection thereof, the operator can determine whether or not the contactor 8 is open.` Thus, in addition to the audible indicator I8 for indicating whether `one of the contactor 8 or the switch I8 isbpen, there is also provided the light 22 for indicating that the switch I0 is open and the visible portions of the latch 28 or its actuating means for indicating whether or not the contactor 8 is open. As a matter of economy, when the overload relay is provided with a visible latch as above described, it will serve to indicate whether or not the contactor 8 is open, the light 22 may be omitted.

In Figure 2 of the drawing there is illustrated a modied form of the invention. In this figure, the parts identical to those shown in Figure l have been indicated by the same reference characters, and further description of these parts will not be made. The principal difference between the circuit shown in Figure 2 and that shown in Figure 1 is that in Figure 2 the overload relay including the contactor 8, the winding 26, and the latch mechanism is omitted. In the form of the invention shown in Figure 2, the control of the charger depends entirely upon vthe operation of the thermostatically actuated switch I0. In this form of invention, however, it is deemed advisable to locate the fuse and the conductors 20 and 2| of the bell-ringing circuit so that if either 4the switch I8 is opened, or the fuse I3 isvblown the bell I8 will ring. In the place of a fuse, a circuit breaker may be employed and may be found more desirable than the fuse in that the closing of the same will be a much simpler operation than the replacement of the fuse. In this instance, therefore, the opening of the circuit breaker would cause the bell circuit to become energized in the same manner as the blowing of a fuse or the opening of the switch I0.

In this form of the invention, the light 22 will serve to indicate whether or not the thermostatically actuated switch I0 is opened, and in this particular form of the invention, the light will be more important than in the circuit illustrated in Figure l. Of course, as the fuse is in a position for easy inspection, the operator may inspect a fuse and lthus determine whether it has blown or the switch I0. With a circuit breaker, the position of the circuit breaker may be visibly ascertained and used as an indication as to whether. the circuit breaker or thc switch I0 is open.

In both forms of the invention shown in Figures 1 and 2, the thermostatically actuated switch I0 must be lconstructed to carry a current sufficient for the proposed operation ofthe charger.`

In the operation of the invention as shown in Figure l, a battery is connected inthe circuit by means of the clips provided for this purpose in the correct polarity and then the main con',- trol switch, which serves to actuateboth switch arms 5 and I1, is actuated to move arm 5 to the first contact 4. This serves to supply powerwto the fan motor and to the primary winding of the transformer. Under these circumstances, the power is Supplied tothe fan andthe primary winding of the transformer l onlyif'the overload relay is in a position in whichythe contactor 8 is closed and the thermostatic switch l'is closed, and the fuse i3 is' intact. Due to the closedfposition of the contactor 8 and the thermostatic switch I0, the transformer l9'is short circuited and insufficient current will iiow through the bell ringing transformer to cause the bell to ring. Thus theA bell will not ring'upon starting the charger.

1f, during" the 'charging of the battery, the

current rises in the output circuit to the trip point of the overload relay, the contactor 8 will be opened and will be held open by themovable releasable latch 28, which'engages the arm 28. This will serve to` cut koff the flow of current through the primary of the transformer and the cooling fan. When contactor 8 opens, it disconnects a good, low impedance path for power to the transformer and fan motor, and only sufficient current will flow through the bell ringing transformer circuit to actuate the bell. This current will be so low that the output charging current will be reduced to zero because the secondary voltage of the transformer l under these circumstances is so low that it cannot charge the battery.

When the above described conditions exist, the operator will be summoned by the bell and will mechanism Ia and lllb so that when the switch is onceopened, itwill not reclose until after a lockout latch is released. The provision of such a. latch on the thermostat would prevent the chargez' from coming on again once the thermostat, which has been left in the battery, cools down with the cooling of .the battery. If an operator were. to leave abattery connected to the charger equipped with an ordinary thermostatwithout .a lockout mechanism thereon foi` quite a few hours, the charger would charge the higher vrate into the battery thusy heating the battery and causing the thermostat to open. After the battery and thermostat cool sufficiently to permit the thermostat to reclose, the charger would again become active land the battery would again-be heated sufficiently lto trip the thermostat. Such a sequence of events'would continue until the, operator reached the scene and turned off the charger. While this would be disadvantageous in some instances. in other cases it would not be a serious drawback because, the time of cooling of the battery would beA considerable. and unless the charger was left unattended for a long period of time, no harm would result. On the other hand, the provision ol the lockout fceture insures that there will be no further action of the charger once .the thermostatically controlled switch I0 has opened.

Thecontrol embodied in the present invention embodies devices which operate without externa1` direct current. The overload relay, for instance, is operated from the direct current circuit, and is normally closed at all times except turn off the main control switch which will stop the ringing of the bell and disconnect the charger from the power line. After ascertaining by inspection that the overload relay has opened the contactor 8, he may release the latch 28 and then again start the charging by moving the main switch to bring the switch arm 5 onto the rst contact 4. Of course, if the charger is equipped with a light such as 22 and the circuit is broken by the opening of the contact 8, then Ithe operator can determine by the absence of operation of the light 22 that it is the contactor B which is open rather than the thermostatic switch I0. On the other hand, if the thermostatic switch Ill .has opened and been the means of breaking the circuit and causing the bell I8 to ring, this can be readily determined by the illumination of the light 22. As hereinbefore explained, however, if the light 22 is omitted and the pawl 2,8 of the overload relay is visible, the operator can determine from the position of the pawl 28 as to whether the contactor 8 or the switch IU has opened.

The fuse i3 is placed in the circuit primarily to protect the transformer in case of a short-circuited rectifier, and will be blown out so seldom that it can be considered a rarity. Consequently, the provision of the bell indicator i8 for signaling the opening of the contactor 8 or the switch l0 is sufficient for the purposes intended.

In some instances it may be desirable to construct the thermostatic switch Hl with a lockout when an overload flows through the direct current charging circuit. The thermostatically controlled switch, on the other hand, is held closed and will open only when it is raised to a temperature sufficiently high to actuate the same. When, for any reason, the connection of the charger to the power line is broken, the fan will stop and the charging current flowing into the battery will be reduced to zero. The charger, however, will remain intact in this form until the alternating current power is again applied. At this time, the transformer and fan will become energized again and the charging will prou ceed.

Aside from the simplicity of the above circuit it should be noted that there are no relays in the charging circuit which need be actuated by battery power. This enables a battery, having no voltage whatever, to be connected to the charger and charged without any external direct current system. Furthermore, the alternating current power may be supplied throughl the secondary of the transformer and the rectier independently of any externally controlled device which might be operated from a battery therefor.

It should also be noted that the control devices operate on the closed circuit principle: That is. if any of the control wires to the tl-icrn'iosiat, which is a portable device on the end of a long7 cable, should be broken, the charger is cut oil. and the operator will be notilied in this manner that there is trouble in the apparatus. if the charger was not made to operate on this closed circuit principle, there might be a faulty ci it including the thermostat and the operator' wiring of the same would connect t le b the charger, and the automatic switch wouicl not to disconnec,v ing circuit when the b y been a predetermined tempt it e. This would i in damage to the battery, by ccinr:

the operator would be watching the operation carefully, and note the excessiveA gassing and failure of the chargervto automatically shut of after a reasonable length of time.

The operation of the charger employing the circuit shown in Figure 2 is substantially identica1vto that of Figure 1, the priricipal difference residing in the omission of the overload relay.`

In this circuit, however; the thermostatically actuated switch I serves as the 'principal'control of the charging operation. Of-course,as hereinbefore explained, the fuse or circuit breaker is d included within the portion .of the circuit, a Ibreak in which operates the indicating means. Furthermore, the fuse or circuit breaker will take care of vany overloads in the circuit.

From the foregoing description, it will be apcndary winding in serieswith the rectifier and 'battery to be charged, a thermostatically actuated switch, responsive to .theelcctrolyte temperature fof a battery under charge, in series with the `connection between the primary winding and l,said supply circuit, indicating means operable upon opening of the primary circuit either by the connection or'the thermostatically actuated switch and other indicating means operablesolely upon opening ofthe thermostatically actuated lswitch. i

2. A battery'charger comprising a transformer -having primary and' secondary windings, a primary circuit includinga contactor `for connectl5 :ing the primary winding to a supply circuit; a rectifier, a secondary circuit connecting\said secondary winding in seriesV withthe rectifier and battery to be charged,l\an actuator for opening said contactor and having anenergizingfwinding in said secondary circuit, a thermostatically actuated switch,` responsiveto the electrolyte connectionbetween the primary winding and said supplyL circuit, indicating means operable temperature of a battery under charge in the upon opening of the primary circuit either by the contactor or .the thermostatically actuated switch, and other indicating means operable solely upon opening of the thermostatically actuated switch. d

CLARENCE' W. DALZELL. 

